Color filter array having color filters, and image sensor and display device including the color filter array

ABSTRACT

A color filter array may include a plurality of color filters arranged two-dimensionally and configured to allow light of different wavelengths to pass therethrough. Each of the plurality of color filters includes at least one Mie resonance particle and a transparent dielectric surrounding the at least one Mie resonance particle.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a is a continuation of U.S. application Ser. No.16/990,747, filed Aug. 11, 2020, which is a continuation of U.S.application Ser. No. 15/456,076 filed Mar. 10, 2017, now U.S. Pat. No.10,739,188, which claims the priority from Korean Patent Application No.10-2016-0029095, filed on Mar. 10, 2016, in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein in itsentirety by reference.

BACKGROUND 1. Field

Apparatuses consistent with exemplary embodiments relate to a colorfilter array, an image sensor including the color filter array, and adisplay device including the color filter array, and, more particularly,to a color filter array including inorganic color filters, an imagesensor including the color filter array, and a display device includingthe color filter array.

2. Description of the Related Art

A color image sensor typically includes organic color filters to detectcolors of light incident thereon. A color display device may use organiccolor filters to display images of various colors. Typically, organiccolor filters are manufactured by forming a black matrix on a glasssubstrate, forming color filter patterns of a plurality of colors suchas red, green, and blue by sequentially using respective dyes orpigments, and planarizing the color filter patterns to level the heightof the color filter patterns. The overall process of manufacturing thecolor filters may be quite complex because the patterning processes areperformed sequentially for each color. Furthermore, since the thicknessof the organic color filters may be large to guarantee a desired colorquality, crosstalk is likely to appear due to light rays obliquelyincident on the organic color filters.

SUMMARY

According to an aspect of an exemplary embodiment, a color filter arrayincludes a plurality of color filters and an isolation wall. Theplurality of color filters are arranged two-dimensionally and transmitlight of different wavelengths. Each of the color filters includes atleast one Mie resonance particle and a transparent dielectricsurrounding the at least one Mie resonance particle. The isolation wallis disposed between adjacent ones of the plurality of color filters toprevent interactions between Mie resonance particles of the adjacentones of the plurality of color filters.

A refractive index of the at least one Mie resonance particle may begreater than a refractive index of the transparent dielectric.

The at least one Mie resonance particle may be formed of a materialselected from a group consisting of germanium (Ge), amorphous silicon(a-Si), polycrystalline silicon (p-Si), crystalline silicon (c-Si),III-V compound semiconductor, titanium dioxide (TiO2), silicon nitride(SiNx), and a combination thereof.

The at least one Mie resonance particle may have a refractive indexgreater than 3.5 at a wavelength of visible light.

The transparent dielectric may be formed of siloxane-based spin on glass(SOG), transparent polymer, silicon dioxide (SiO₂), or air.

The material forming the isolation wall may be different from thematerial forming the transparent dielectric.

The isolation wall may be formed of a material selected from a groupconsisting of tungsten (W), aluminum (Al), gold (Au), silver (Ag),titanium (Ti), nickel (Ni), platinum (Pt), an alloy thereof, titaniumnitride (TiN), air, and a combination thereof.

A thickness of each of the plurality of color filters may be in a rangefrom about 200 nm to about 300 nm.

An aspect ratio of each of the at least one Mie resonance particle maybe in a range from about 0.5 to about 6.

The plurality of color filters may include a first color filterconfigured to transmit light of a first wavelength range; and a secondcolor filter configured to transmit light of a second wavelength rangedifferent from the first wavelength range. A shape, a size, and athickness of the at least one Mie resonance particle of the first colorfilter and a distance between the Mie resonance particles of the firstcolor filter may be chosen such that the light of the first wavelengthrange is transmitted. Also, a shape, a size, and a thickness of the atleast one Mie resonance particle of the second color filter and adistance between the Mie resonance particles of the second color filtermay be chosen such that the light of the second wavelength range istransmitted.

Each of the plurality of color filters may include a plurality of unitcells each of which comprises a plurality of Mie resonance particles.The plurality of unit cells may be arranged periodically within each ofthe plurality of the plurality of color filters. The plurality of Mieresonance particles may be arranged irregularly within each of theplurality of unit cells.

The isolation wall may include a plurality of isolation members arrangedalong boundaries of each of the plurality of color filters. Theplurality of isolation members may be spaced apart from each other.

Each of the plurality of color filters may include four first Mieresonance particles. Each of the first Mie resonance particles may havea quarter circular shape and be disposed at a corner of each of theplurality of color filters.

Each of the plurality of color filters may further include a second Mieresonance particle. The second Mie resonance particle may have acircular shape and be disposed at center portion of each of theplurality of color filters.

Each of the plurality of color filters may include a square shaped Mieresonance particle. The square shaped Mie resonance particle may bedisposed at center portion of each of the plurality of color filters.

According to an aspect of another exemplary embodiment, an image sensorincludes: a light sensing layer including an array of a plurality ofpixels arranged two-dimensionally and configured to detect light ofdifferent wavelength ranges; and a color filter array disposed on thelight sensing layer and configured to include a plurality of colorfilters arranged two-dimensionally and configured to transmit the lightof different wavelengths. Each of the plurality of color filtersincludes at least one Mie resonance particle and a transparentdielectric surrounding the at least one Mie resonance particle. Thecolor filter array includes an isolation wall arranged between adjacentones of the plurality of color filters and configured to preventinteractions between Mie resonance particles of the adjacent ones of theplurality of color filters.

According to another aspect of another exemplary embodiment, an imagesensor includes: a first light sensing layer including a first pixelconfigured to absorb and detect light of a first wavelength range and totransmit light outside of the first wavelength range; a second lightsensing layer facing the first light sensing layer and including asecond pixel configured to detect light of a second wavelength range anda third pixel configured to detect light of a third wavelength range;and a color filter array disposed between the first light sensing layerand the second light sensing layer and including a second color filterfacing the second pixel and configured to transmit the light of thesecond wavelength range and a third color filter facing the third pixeland configured to transmit the light of the third wavelength range. Eachof the second color filter and the third color filter includes at leastone Mie resonance particle and a transparent dielectric surrounding theat least one Mie resonance particle. The color filter array includes anisolation wall arranged between the second color filter and the thirdcolor filter and configured to prevent interactions between Mieresonance particles of the second color filter and Mie resonanceparticles of the third color filter.

The image sensor may further include: a plurality of color separationelements disposed between the first light sensing layer and the colorfilter array and configured to direct the light of the second wavelengthrange transmitted through the first light sensing layer toward thesecond pixel and direct the light of the third wavelength rangetransmitted through the first light sensing layer toward the thirdpixel.

The image sensor may further include: a plurality of driving signallines extending from the second light sensing layer to the first lightsensing layer and configured to transmit driving signals to the firstlight sensing layer or receive data signals from the first light sensinglayer.

For example, the isolation wall may be formed of a conductive metallicmaterial, and the plurality of driving signal lines may extend to thefirst light sensing layer through the isolation wall.

According to an aspect of another exemplary embodiment, a display deviceincludes: a pixel array including a plurality of display pixels arrangedtwo-dimensionally and configured to display an image; and a color filterarray disposed on the pixel array and including a plurality of colorfilters arranged two-dimensionally and configured to transmit light ofdifferent wavelengths. Each of the plurality of color filters includesat least one Mie resonance particle and a transparent dielectricsurrounding the at least one Mie resonance particle. The color filterarray includes an isolation wall arranged between adjacent ones of theplurality of color filters and configured to prevent interactionsbetween Mie resonance particles of the adjacent ones of the plurality ofcolor filters.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other exemplary aspects and advantages will become apparentand more readily appreciated from the following description of theexemplary embodiments, taken in conjunction with the accompanyingdrawings in which:

FIG. 1 is a cross-sectional view schematically illustrating a colorfilter array according to an exemplary embodiment;

FIG. 2 is a plan view schematically illustrating a color filter arrayaccording to an exemplary embodiment;

FIG. 3 is a plan view schematically illustrating a color filter arrayaccording to another exemplary embodiment;

FIG. 4 is a cross-sectional view schematically illustrating a colorfilter array according to another exemplary embodiment;

FIG. 5 is a plan view illustrating an exemplary arrangement of Mieresonance particles in a color filter array according to anotherexemplary embodiment;

FIGS. 6 through 8 are graphs illustrating exemplary transmittancespectra of each color filter according to arrangements of Mie resonanceparticles;

FIGS. 9 and 10 are plan views illustrating exemplary structures of anisolation wall in a color filter array according to another exemplaryembodiments;

FIG. 11 is a cross-sectional view illustrating an exemplary structure ofan isolation wall in a color filter array according to another exemplaryembodiment;

FIG. 12 is a cross-sectional view schematically illustrating an imagesensor according to an exemplary embodiment that employs the colorfilter array according to the above exemplary embodiments;

FIG. 13 is a cross-sectional view schematically illustrating an imagesensor according to another exemplary embodiment, which includes thecolor filter array according to the above exemplary embodiments;

FIG. 14 is a cross-sectional view schematically illustrating an imagesensor according to yet another exemplary embodiment which includes thecolor filter array according to the above exemplary embodiments;

FIG. 15 is a cross-sectional view schematically illustrating an imagesensor according to yet another exemplary embodiment which includes thecolor filter array according to the above exemplary embodiments;

FIG. 16 is a cross-sectional view schematically illustrating an imagesensor according to yet another exemplary embodiment which includes thecolor filter array according to the above exemplary embodiments;

FIG. 17 is a cross-sectional view schematically illustrating an imagesensor according to yet another exemplary embodiment which includes thecolor filter array according to the above exemplary embodiments;

FIG. 18 is a cross-sectional view schematically illustrating an imagesensor according to yet another exemplary embodiment which includes thecolor filter array according to the above exemplary embodiments;

FIG. 19 is a plan view schematically illustrating a color filteraccording to another exemplary embodiment;

FIGS. 20A through 20E are graphs illustrating exemplary transmittancespectra of each color filter according to diameters of Mie resonanceparticles;

FIG. 21 is a plan view schematically illustrating a color filteraccording to yet another exemplary embodiment; and

FIGS. 22A through 22E are graphs illustrating exemplary transmittancespectra of each color filter according to a width of a Mie resonanceparticle.

DETAILED DESCRIPTION

Hereinbelow, a color filter array including an inorganic color filter,an image sensor including the color filter array, and a display deviceincluding the color filter array will be described in detail withreference to the accompanying drawings. In the drawings, like referencenumbers refer to like elements throughout, and the size of each elementmay be exaggerated for clarity of illustration. Exemplary embodimentsdescribed herein are for illustrative purposes only, and variousmodifications may be made therefrom. In the following description, whenan element is referred to as being “above” or “on” another element in alayered structure, it may be directly on, under, or lateral to the otherelement while making contact with the other element or may be above,below, or lateral to the other element without making contact with theother element.

While the use of a black matrix, as discussed above, is not uncommon indisplay devices, the role of a black matrix in such devices is toprevent backlight from passing through gaps between pixels. In contrast,in image sensors, a metal grid, such as one of tungsten, may be used.However, since microlenses disposed on top of image sensor color filtersmay prevent crosstalk between color filters, the use of such a metalgrid is optional. A metal grid may provide electrical stability bypreventing unwanted charge accumulations at the pixels, but may alsocause significant, undesirable degradation of quantum efficiencybecause, unlike display pixels which are comparatively large, imagesensor pixels may be only micron-sized. The use of a metal grid may alsoreduce infrared sensitivity and thus provide a slight decrease inspectral crosstalk. Accordingly, the role of the isolation wallsdescribed herein may be different from that of a metal grid, in that theisolation walls may reduce near field interactions between neighboringMie resonators at pixel boundaries and also minimize lateral flow oflight propagation due to scattering from the Mie resonators.

FIG. 1 is a cross-sectional view schematically illustrating a colorfilter array 10 according to an exemplary embodiment. Referring to FIG.1 , the color filter array 10 according to an exemplary embodiment mayinclude a plurality of color filters 10A, 10B, and 10C arranged in atwo-dimensional array, to transmit light of different wavelengths, andan isolation wall 13 arranged between the color filters 10A and 10B, andbetween the color filters 10B and 10C. Each of the color filters 10A,10B, and 10C may include a plurality of Mie resonance particles 12 andtransparent dielectrics 11 sandwiching the plurality of Mie resonanceparticles 12.

The Mie resonance particles 12 may be disposed in each of the colorfilters 10A, 10B, and 10C in various manners. In general, ‘Mieresonance’ or ‘Mie scattering’ refers to a scattering phenomenon thathappens at a particle having a size dimension comparable to thewavelength of incident light. According to the ‘Mie resonance’ or ‘Miescattering’, an optical resonance occurs in a certain wavelength rangedetermined by conditions of the particle, and the light in the certainwavelength range is strongly scattered by the particle. In the presentexemplary embodiment, color characteristics of each of the color filters10A, 10B, and 10C is determined by the shapes, sizes, and thickness ofthe Mie resonance particles and distances between the Mie resonanceparticles in the respective color filters 10A, 10B, and

For example, the shapes, sizes, and thicknesses of the Mie resonanceparticles 12 and the distances between the Mie resonance particles 12 inthe first color filter 10A may be configured such that the first colorfilter 10A may transmit light of a first wavelength range. Accordingly,of the light incident on the first color filter 10A, only the light ofthe first wavelength range may be transmitted through the first colorfilter 10A and the light of a second and third wavelength ranges may bereflected or absorbed by the first color filter 10A, because ofresonance scatterings of individual Mie resonance particles 12 andresonances and diffractions due to interactions of adjacent Mieresonance particles 12.

Also, the shapes, sizes, and thicknesses of the Mie resonance particles12 and the distances between the Mie resonance particles in the secondcolor filter 10B may be configured such that the second color filter 10Bmay transmit light of the second wavelength range different from thefirst wavelength range. Accordingly, of the light incident on the secondcolor filter 10B, only the light of the second wavelength range may betransmitted through the second color filter 10B and the light of thefirst and third wavelength ranges may be reflected or absorbed by thesecond color filter 10B because of the resonance scatterings ofindividual Mie resonance particles 12 and the resonances and thediffractions due to the interactions of adjacent Mie resonance particles12.

Similarly, the shapes, sizes, and thicknesses of the Mie resonanceparticles 12 and the distances between the Mie resonance particles inthe third color filter 10C may be configured such that the third colorfilter 10C may transmit light of the third wavelength range differentfrom the first and second wavelength ranges. Accordingly, of the lightincident on the third color filter 10C, only the light of the thirdwavelength range may be transmitted through the third color filter 10Cand the light of the first and second wavelength ranges may be reflectedor absorbed by the third color filter 10C because of the resonancescatterings of individual Mie resonance particles 12 and the resonancesand the diffractions due to the interactions of adjacent Mie resonanceparticles 12.

The Mie resonance particles 12 may be disposed in the transparentdielectric 11 in any of various manners. A refractive index of the Mieresonance particles 12 may be greater than that of a surroundingmaterial to ensure a high resonance efficiency. Thus, the refractiveindex of the Mie resonance particles 12 may be greater than that of thetransparent dielectric 11. For example, the transparent dielectric 11may be formed of siloxane-based spin on glass (SOG), transparentpolymer, silicon dioxide (SiO2), or air, and the Mie resonance particles12 may be formed of a material having a high refractive index such asgermanium (Ge), amorphous silicon (a-Si), polycrystalline silicon(p-Si), crystalline silicon (c-Si), III-V compound semiconductor,titanium dioxide (TiO2), and silicon nitride (SiNx). In particular, theMie resonance particles 12 formed of a material with a refractive indexgreater than 3.5 in a visible light wavelength range may be used toenhance the resonance efficiency.

A diameter or a length of one side of each Mie resonance particle 12 mayrange from about 40 nanometers (nm) to about 500 nm to facilitate theMie resonance. The Mie resonance particles 12 may have various shapessuch as a sphere, an ellipsoid, and a polyhedron, for example, but theshapes of the Mie resonance particles 12 are not limited thereto. Thethickness of the Mie resonance particles 12 may range from about 50 nmto about 300 nm, and the aspect ratio may range from about 0.5 to about6.

The isolation wall 13 prevents interactions of the Mie resonanceparticles 12 in two or more adjacent color filters 10A, 10B, and 10C.Without the isolation wall 13, the Mie resonance particles 12 in thecolor filter 10A, 10B, or 10C may interact with the Mie resonanceparticles 12 in an adjacent color filter and thereby affect theresonance characteristics of respective color filters 10A, 10B, and 10C.As a result, light having a wavelength outside the wavelength range setfor each of the color filters 10A, 10B, and 10C may be scattered. Theisolation wall 13 may be formed of a material different from that of thetransparent dielectric 11 so as to isolate the Mie resonance particles12 in the adjacent color filters 10A, 10B, and 10C. For example, theisolation wall 13 may be formed of: a metallic material such as tungsten(W), aluminum (Al), gold (Au), silver (Ag), titanium (Ti), nickel (Ni),platinum (Pt), and an alloy thereof; a dielectric material such astitanium nitride (TiN); or the air. In case that the transparentdielectric 11 is air, the isolation wall 13 may be formed of any of theabove material other than the air. Since the interaction of the Mieresonance particles 12 across the isolation wall 13 is minimized owingto the isolation wall 13, each of the color filters 10A, 10B, and 10Cmay maintain the desired transmission characteristics.

FIG. 2 is a plan view schematically illustrating the color filter array10 according to an exemplary embodiment. Although it is shown in FIG. 1, for exemplary purposes, that three color filters 10A, 10B, and 10C arearranged in series, the number and arrangement of the color filters 10A,10B, and 10C are not limited thereto but may be altered as needed. Forexample, it is shown in the planar view of FIG. 2 that four colorfilters 10A-10D, placed in a rectangular arrangement, constitute a unitpattern. However, the arrangement shown in FIG. 2 is also provided onlyfor exemplary purposes.

Referring to FIG. 2 , the isolation wall 13 may form a grating structurethat completely encloses each of the color filters 10A-10D. In each ofthe color filters 10A-10D, a plurality of Mie resonance particles 12 maybe arranged regularly at a certain period. The arrangement period,sizes, and shapes of the Mie resonance particles 12 in any one of thecolor filters 10A-10D may be different from those of the Mie resonanceparticles 12 in any other color filter, so that the light transmissioncharacteristics of the four the color filters 10A-10D may be differentfrom one another. It is shown in FIG. 2 that the Mie resonance particles12 disposed in each of the first through third color filters 10A-10Chave the same shapes but have different arrangement periods and sizes inthe each of the color filters, and the Mie resonance particles 12disposed in the fourth color filter 10D have an arrangement period,size, and shape different from the particles in the first through thirdcolor filters 10A-10C. However, the arrangement periods, sizes, andshapes of the Mie resonance particles 12 are not limited to the exampleshown in FIG. 2 . Furthermore, the Mie resonance particles 12 in onecolor filter 10A, 10B, 10C, or 10D may have sizes and shapes differentfrom one another. In other words, the Mie resonance particles 12 havingvarious sizes and shapes may exist even in each of the color filters10A-10D.

FIG. 3 is a plan view schematically illustrating the color filter array10 according to another exemplary embodiment. Although it is shown inFIG. 2 that the Mie resonance particles 12 are disposed periodically,the arrangement of the Mie resonance particles 12 is not limitedthereto. As shown in FIG. 3 , for example, the Mie resonance particles12 may be disposed irregularly within each of the color filters 10A-10D.That is, the shapes, sizes, and arrangement pattern of the Mie resonanceparticles 12 may be chosen freely to meet the color characteristics setfor each of the color filters 10A-10D. For example, the shapes, sizes,and arrangement patterns of the Mie resonance particles 12 for each ofthe color filters 10A-10D may be determined using a computer simulation,so that each of the color filters 10A-10D may have respectively desiredcolor characteristics.

Although it is shown in FIGS. 2 and 3 that the four color filters10A-10D disposed in a rectangular shape have color characteristics whichare different from one another, the color characteristics of the colorfilters is not limited thereto. For example, in case that the colorfilter array 10 has a Bayer pattern structure, the color filters 10A-10Dmay be designed such that the first color filter 10A and the fourthcolor filter 10D, disposed diagonally, transmit green light, the secondcolor filter 10B transmits red light, and the third color filter 10Ctransmits blue light. In such a case, the shape, size, and arrangementpattern of the Mie resonance particles 12 in the first color filter 10Amay be the same as those of the particles in the fourth color filter10D.

FIG. 4 is a cross-sectional view schematically illustrating a colorfilter array 10 according to another exemplary embodiment. In FIG. 1 ,all the three color filters 10A, 10B, and 10C and the Mie resonanceparticles 12 in the three color filters 10A, 10B, and 10C have samethickness ‘h’. In order to obtain desired resonance characteristics,however, the thicknesses of the Mie resonance particles 12 may bevaried. For example, the thicknesses of the Mie resonance particles 12in three color filters 10A, 10B, and 10C may be different from oneanother as shown in FIG. 4 . Furthermore, although it is shown in FIG. 4that the Mie resonance particles 12 disposed in one of the color filters10A, 10B, and 10C have the same thickness, the Mie resonance particles12 within a single color filter may have thicknesses different from eachother as needed.

FIG. 5 is a plan view illustrating an exemplary arrangement of Mieresonance particles 12 in a color filter array 10 according to anotherexemplary embodiment. Although only a single color filter is shown inFIG. 5 , for convenience of description, the structure shown in FIG. 5may be applied to any of the color filters 10A-10D. Referring to FIG. 5, each of the color filters 10A-10D may be configured to include aplurality of unit cells 14, each of which includes a plurality of Mieresonance particles 12. The plurality of Mie resonance particles 12 ineach of the unit cells 14 may be arranged irregularly. The plurality ofunit cells 14 in each of the color filters 10A-10D may be disposedregularly, within the color filter, to have a certain period, but theperiods of arranging the unit cells 14 may differ among the colorfilters 10A-10D. In such a structure, the resonance characteristics ofeach color filter 10A, 10B, 10C, or 10D may depend on the respectiveperiods of the unit cells 14. Also, even when the arrangement periods ofthe unit cells 14 are the same in each of the color filters 10A-10D, theresonance characteristics of each color filter 10A, 10B, 10C, or 10D maydepend on the shapes, sizes, and arrangement patterns of the Mieresonance particles 12 within the unit cells 14. Accordingly, the colorcharacteristics of the color filters 10A-10D may be precisely determinedas needed by selecting a suitable combination of the shapes, sizes, andarrangement patterns of the Mie resonance particles 12, as well as thearrangement periods of the unit cells 14.

FIGS. 6 through 8 are graphs illustrating exemplary transmittancespectra for each color filter according to arrangements of the Mieresonance particles 12. In the color filters of FIGS. 6 through 8 , theMie resonance particles 12 formed of polysilicon were used, and thethicknesses, arrangement periods, and widths of the Mie resonanceparticles 12 were differentiated among the color filters correspondingto FIGS. 6 through 8 , respectively. In the drawings, the horizontalaxis measures the wavelength of incident light and the transmittance isplotted on the vertical axis. For comparison, the transmittancecharacteristics of related art organic color filters are plottedtogether as graphs designated by legends B′, G′, and R′.

First, FIG. 6 illustrates a transmittance spectrum in a case in whichthe thickness of the Mie resonance particles 12 is 200 nm, thearrangement period is 260 nm, and the width is 130 nm. As shown by asolid line graph designated by a legend B, the color filter transmitsmost of the blue light while absorbing or reflecting the red light andgreen light. FIG. 7 illustrates a transmittance spectrum in the casethat the thickness of the Mie resonance particles 12 is 200 nm, thearrangement period is 320 nm, and the width is 170 nm. As shown by asolid line graph designated by a legend G, the color filter transmitsmost of the green light while absorbing or reflecting the blue light andthe red light. FIG. 8 illustrates a transmittance spectrum in the casethat the thickness of the Mie resonance particles 12 is 150 nm, thearrangement period is 260 nm, and the width is 220 nm. As shown by asolid line graph designated by a legend R, the color filter transmitsmost of the red light while absorbing or reflecting the blue light andgreen light. Consequently, the transmittance spectrum of a color filtermay be adjusted precisely by changing the shape, size, period, andarrangement pattern of the Mie resonance particles 12.

On the other hand, although the isolation wall 13 was described above toform a grating structure which completely encloses each of the colorfilters 10A-10D, the structure or shape of the isolation wall 13 is notlimited thereto. An isolation wall 13 of any shape may be used as longas the isolation wall 13 obstructs interactions between the Mieresonance particles 12 belonging to the adjacent color filters 10A-10D.For example, FIGS. 9 and 10 are plan views illustrating exemplarystructures of the isolation wall 13 in the color filter array 19according to another exemplary embodiment. As shown in FIG. 9 , theisolation wall 13 may be cut near the vertices of each color filter 10A,10B, 10C, or 10D, such that there are gaps in the isolation wall 13 atthe corners of each of the color filters. Thus, the isolation wall 13may be disposed only at the sides of each color filter 10A, 10B, 10C, or10D, such that the isolation wall 13 is divided discontinuously into aplurality of portions. Also, referring to FIG. 10 , the isolation wall13 may include a plurality of isolation members 13A disposed alongboundaries of each of the color filters 10A-10D. The plurality ofisolation members 13A may have cross sections in any shape, such as acircle and a polygon, and may be spaced apart from each other by acertain distance. While one isolation wall 13 is disposed at each sideof the color filters 10A-10D in the example of FIG. 9 , a plurality ofisolation members 13A are disposed at each side of the color filters10A-10D in the example of FIG. 10 .

FIG. 11 is a cross-sectional view illustrating an exemplary structure ofan isolation wall 13 in a color filter array 10 according to anotherexemplary embodiment. As shown in FIG. 11 , air may be used as anisolation material of the isolation wall 13. In this case, two adjacentdielectric layers 11 may be spaced apart by a certain gap, and the gapbetween the two adjacent dielectric layers 11 may be filled with air,thus forming the isolation wall.

As described above, the color filter array 10 according to the disclosedembodiments are inorganic color filter array that utilizes Mie resonanceparticles 12. the manufacturing of such a color filter array 10 does notrequire the use of dyes or pigments, and the colors filters 10A-10D forall colors may be formed simultaneously by using common lithography andpatterning techniques. Thus, the manufacturing process of the colorfilter array 10 according to the disclosed exemplary embodiments may besimplified as compared to the manufacturing process of a related artorganic color filter. Also, the thickness of each color filter 10A, 10B,10C, or 10D in the color filter array 10 may be reduced since the colorcharacteristics of each color filter 10A, 10B, 10C, or 10D may beadjusted easily according to the shape, size, thickness, and arrangementpatterns of the Mie resonance particles 12 disposed therein. Forexample, the thickness of each color filter 10A, 10B, 10C, or 10D in acolor filter array 10 according to an exemplary embodiment disclosedherein ranges from about 200 nm to 300 nm. Accordingly, when the colorfilter array 10 according to an exemplary embodiment disclosed herein isinstalled in an image sensor or a display device, the crosstalk causedby light incident obliquely may be suppressed.

FIG. 12 is a cross-sectional view schematically illustrating an imagesensor 100 according to an exemplary embodiment that employs the colorfilter array 10 according to the exemplary embodiments discussed above.Referring to FIG. 12 , an image sensor 100 may include a light sensinglayer 110 configured to convert the intensity of incident light into anelectrical signal, the color filter array 10 having a plurality of colorfilters 10A-10C disposed on the light sensing layer 110, and a pluralityof microlenses 130 disposed on the color filter array 10. Also, theimage sensor 100 may further include an antireflection layer 120disposed between the light sensing layer 110 and the color filter array10, as needed, to prevent the reflection of light incident from thecolor filter array 10 onto the light sensing layer 110.

The light sensing layer 110 includes a plurality of independent pixels110A, 110B, and 110C arranged in a two-dimensional array, and the pixelsadjacent to each other may be separated by a trench 111. A separatecolor filter 10A, 10B, or 10C may be provided for each of the pixels110A-110C. For example, the first color filter 10A transmitting light ofthe first wavelength range may be disposed on a first pixel 110A, thesecond color filter 10B transmitting light of the second wavelengthrange may be disposed on a second pixel 110B, and the third color filter10C transmitting light of the third wavelength range may be disposed ona third pixel 110C. Accordingly, the first pixel 110A may detect anintensity of the light of the first wavelength range, the second pixel110B may detect an intensity of the light of the second wavelengthrange, and the third pixel 110C may detect an intensity of the light ofthe third wavelength range. The plurality of microlenses 130 arearranged so as to focus the incident light on respectively correspondingpixels 110A-110C.

Although FIG. 12 illustrates a case in which the color filter array 10is installed in an image sensor 100, the color filter array 10 may beapplied similarly to a display device as well. In such a case, thepixels 110A-110C shown in FIG. 12 may be display pixels for displayingimages rather than light sensing pixels which detect light incidentthereon. The display pixels may be provided in a liquid crystal layer,for example, or in an organic light emitting layer that emits whitelight. In a case in which the color filter array 10 is applied to adisplay device, the microlens disposed on the color filter array 10 maybe omitted.

FIG. 13 is a cross-sectional view schematically illustrating an imagesensor 200 according to another exemplary embodiment that employs thecolor filter array 10 discussed above. Referring to FIG. 13 , the imagesensor 200 may include a first light sensing layer 140 including aplurality of first pixels 110A absorbing and detecting light of a firstwavelength range and transmitting light of other wavelength ranges, asecond light sensing layer 145 including a plurality of second pixels110B detecting light of a second wavelength range, and a plurality ofthird pixels 110C detecting light of a third wavelength range, and thecolor filter array 10 disposed between the first light sensing layer 140and the second light sensing layer 145. Also, the image sensor 200 mayfurther include an antireflection layer 120 disposed between the secondlight sensing layer 145 and the color filter array 10 to prevent thereflection of light incident from the color filter array 10 onto thesecond light sensing layer 145.

The first light sensing layer 140 and the second light sensing layer 145may be stacked as shown in FIG. 13 . More specifically, the color filterarray 10 may be disposed on an upper surface of the second light sensinglayer 145, and the first light sensing layer 140 may be disposed on anupper surface of the color filter array 10, such that the first lightsensing layer 140 is disposed opposite the second light sensing layer145. In this case, the first light sensing layer 140 and the secondlight sensing layer 145 may be configured to detect different wavelengthranges of light. Particularly, the first light sensing layer 140 may beconfigured to absorb only light of a first wavelength range to bedetected and may transmit light of second and third wavelength ranges.

For example, the first light sensing layer 140 may absorb only light ofa green wavelength range and transmit light of red and blue wavelengthranges. The first light sensing layer 140 having such characteristicsmay include a material such as a rhodamine-based pigment, amerocyanine-based pigment, or quinacridone. In the present exemplaryembodiments, however, the absorption wavelength range of the first lightsensing layer 140 is not limited to a green wavelength range.Alternatively, the first light sensing layer 140 may be configured toabsorb and detect only light of a red wavelength range and transmitlight of blue and green wavelength ranges. Alternatively, the firstlight sensing layer 140 may absorb and detect only light of a bluewavelength range and transmit light of green and red wavelength ranges.For example, the first light sensing layer 140 may include aphthalocyanine-based pigment to detect light of a red wavelength range,or may include a material such as a coumarin-based pigment,tris-(8-hydroxyquinoline)aluminum (Alq₃), or a merocyanine-based pigmentto detect light of a blue wavelength range.

As described above, light of a first wavelength range incident on theimage sensor 200 is absorbed by the first light sensing layer 140, andonly light of second and third wavelength ranges may be transmittedthrough the first light sensing layer 140. Light of second and thirdwavelength ranges that is transmitted through the first light sensinglayer 140 may be incident on the color filter array 10. The color filterarray 10 may include the second color filter 10B disposed on the secondpixel 110B and configured to transmit only light of a second wavelengthrange, and the third color filter 10C disposed on the third pixel 110Cand configured to transmit only light of a third wavelength range.Accordingly, of light of the second and third wavelength ranges that istransmitted through the first light sensing layer 140, light of thesecond wavelength range may be transmitted through the second colorfilter 10B and be incident on the second pixel 110B in the second lightsensing layer 145. Also, of the light transmitted through the firstlight sensing layer 140, light of a third wavelength range may betransmitted through the third color filter 10C and be incident on thethird pixel 110C in the second light sensing layer 145.

In addition, the image sensor 200 may further include a firsttransparent electrode 141 and a second transparent electrode 142respectively disposed on a lower surface and an upper surface of thefirst light sensing layer 140, a plurality of microlenses 130 disposedon top of the second transparent electrode 142, and driving signal lines112 suitable for transmitting driving signals to the first light sensinglayer 140 or receiving data signals from the first light sensing layer140. For example, the first transparent electrode 141 may be a pixelelectrode providing a driving signal, independently, to each of thefirst pixels 110A in the first light sensing layer 140. In this case, aplurality of first transparent electrodes 141 may be disposed separatelyfor respectively corresponding first pixels 110A. The second transparentelectrode 142 may be a common electrode shared by all the first pixels110A in the first light sensing layer 140. The first and secondtransparent electrodes 141 and 142 may be formed of, for example, atransparent conductive oxide such as indium tin oxide (ITO), indium zincoxide (IZO), aluminum zinc oxide (AZO), and gallium zinc oxide (GZO).

A driving circuit (not shown in the cross-sectional view of FIG. 13 )may be disposed under the second light sensing layer 145 to controloperations of the first light sensing layer 140 and the second lightsensing layer 145 and to process data received from the first lightsensing layer 140 and the second light sensing layer 145. The drivingsignal lines 112 connect the driving circuit disposed under the secondlight sensing layer 145 to the first light sensing layer 140. Forexample, the driving signal lines 112 may be disposed along the trench111 between the second pixel 110B and the third pixel 110C. Also, thedriving signal lines 112 may penetrate the antireflection layer 120 tobe connected to the isolation wall 13 of the color filter array 10. Inthis case, the isolation wall 13 may be formed of conductive metal so asto be electrically connected to the first transparent electrode 141.Meanwhile, the isolation wall 13 may have a discontinuous structure asshown in FIG. 9 or FIG. 10 so that the isolation wall 13 is electricallyconnected to only one of the first transparent electrodes 141corresponding thereto. Accordingly, the driving signal lines 112 mayextend to the first light sensing layer 140 through the isolation wall13 in the color filter array 10.

According to the image sensor 200 of the present exemplary embodiments,the number of pixels per unit area may be increased since the firstlight sensing layer 140 and the second light sensing layer 145 arearranged in a stacked manner. Therefore, the resolution of the imagesensor 200 may be enhanced. Furthermore, the loss of light may bereduced since the first light sensing layer 140 absorbs and detects mostof the light of a first wavelength range and transmits most of the lightof second and third wavelength ranges and the second light sensing layer145 detects light of the second and third wavelength ranges transmittedthrough the first light sensing layer 140. Therefore, most of the lightof the first through third wavelength ranges may be used efficiently,and the sensitivity of the image sensor 200 may be improved in allwavelength ranges.

FIG. 14 is a cross-sectional view schematically illustrating an imagesensor 300 according to another exemplary embodiment that employs thecolor filter array 10 discussed above. Referring to FIG. 14 , an imagesensor 300 may include a first light sensing layer 140 including aplurality of first pixels 110A absorbing and detecting light of a firstwavelength range and transmitting light of other wavelength ranges, asecond light sensing layer 145 including a plurality of second pixels110B detecting light of a second wavelength range and a plurality ofthird pixels 110C detecting light of a third wavelength range, atransparent spacer layer 150 disposed between the first light sensinglayer 140 and the second light sensing layer 145, a color separationelement 151 disposed in the transparent spacer layer 150, and a colorfilter array 10 disposed between the transparent spacer layer 150 andthe second light sensing layer 145. Also, the image sensor 300 mayfurther include an antireflection layer 120 disposed between the secondlight sensing layer 145 and the color filter array 10 to prevent thereflection of the light incident from the color filter array 10 onto thesecond light sensing layer 145.

As discussed above with reference to FIG. 13 , light of a firstwavelength range incident on the image sensor 300 is absorbed by thefirst light sensing layer 140, and only light of the second and thirdwavelength ranges may be transmitted through the first light sensinglayer 140. In the image sensor 300 of FIG. 14 , light of the second andthird wavelength ranges that is transmitted through the first lightsensing layer 140 may be incident on the transparent spacer layer 150and separated by the color separation element 151. The color separationelement 151 is disposed at a light entrance side of the second lightsensing layer 145 to separate incident light according to wavelength sothat light of different wavelengths may enter pixels corresponding tothe respectively wavelengths. The color separation element 151 mayseparate colors of incident light by changing the propagation directionof light according to wavelength by using diffraction or refractionproperties of light that vary according to wavelength. For thisoperation, the color separation element 151 may be formed of a materialhaving a refractive index greater than that of the spacer layer 150surrounding the color separation element 151. For example, the spacerlayer 150 may be formed of silicon dioxide (SiO₂) or siloxane-basedspin-on-glass (SOG), and the color separation element 151 may be formedof a material having a high refractive index such as titanium dioxide(TiO₂), silicon nitrides (SiN_(x), Si₃N₄), zinc sulfide (ZnS), and zincselenide (ZnSe). Various structures such as a transparent symmetric orasymmetric bar structure and a prism structure having a slanted surfaceare known in the art as structures suitable for the color separationelement. Thus, the structure of the color separation element 151 may bedesigned in any of various manners according to the desired spectrum ofexiting light.

As shown in FIG. 14 , the color separation element 151 may be configuredto separate the light incident thereon into light C2 of a secondwavelength range and light C3 of a third wavelength range, so that lightC2 of the second wavelength range propagates to the second pixel 110B inthe second light sensing layer 145 and light C3 of the third wavelengthrange propagates to the third pixel 110C. For example, the colorseparation element 151 may be designed to change the propagationdirection of light C2 of the second wavelength range into obliquedirections facing laterally downwards while not changing the propagationdirection of light C3 of the third wavelength range. Then, light C3 ofthe third wavelength range may be incident on the third pixel 110Clocated directly under the color separation element 151, and light C2 ofthe second wavelength range may be incident on the second pixels 110Blocated at lateral sides of the color separation element 151. As aresult, the second pixels 110B located at lateral sides of the colorseparation element 151 may detect light C2 of the second wavelengthrange, and the third pixels 110C located under the color separationelement 151 may detect light C3 of the third wavelength band.

In the exemplary embodiment shown in FIG. 14 , light C2 of the secondwavelength range separated by the color separation element 151 isincident on the second color filters 10B and may be transmitted throughthe second color filters 10B with little loss. Similarly, light C3 ofthe third wavelength range separated by the color separation element 151is incident on the third color filter 10C and may be transmitted throughthe third color filter 10C with little loss. Meanwhile, the first lightsensing layer 140 may absorb almost all light of a first wavelengthrange. Therefore, light of the first through third wavelength ranges maybe used efficiently. As a consequence, the sensitivity of the imagesensor 300 may be enhanced in all wavelength ranges. Further, since thecolor separation element 151 may be configured to separate light of onlytwo wavelength ranges, the color separation element 151 may be easilydesigned and manufactured.

FIG. 15 is a cross-sectional view schematically illustrating an imagesensor 400 according to yet another exemplary embodiment that employsthe color filter array 10 discussed above. Referring to FIG. 15 , theimage sensor 400 may include a light sensing layer 110 having aplurality of pixels 110A, 110B, and 110C separated by a trench 111, anantireflection layer 120 disposed on the light sensing layer 110, andthe color filter array 10. The color filter array 10 may include aplurality of color filters 10A, 10B, and 10C and an isolation wall 13arranged between the color filters 10A and 10B, and between the colorfilters 10B and 10C. The isolation wall 13 may be air. Each of the colorfilters 10A, 10B, and 10C may include a plurality of Mie resonanceparticles 12 and a transparent dielectric 11 surrounding the pluralityof Mie resonance particles 12. The transparent dielectric 11 maycompletely covers upper surfaces of the plurality of Mie resonanceparticles 12.

FIG. 16 is a cross-sectional view schematically illustrating an imagesensor 500 according to yet another exemplary embodiment that employsthe color filter array 10 discussed above. Referring to FIG. 16 , theimage sensor 500 has the same structure as the image sensor 400, exceptthat each of the color filters 10A, 10B, and 10C further includes amicrolens 130 disposed on the transparent dielectric 11.

FIG. 17 is a cross-sectional view schematically illustrating an imagesensor 600 according to yet another exemplary embodiment that employsthe color filter array 10 discussed above. Referring to FIG. 17 , theimage sensor 600 has the same structure as the image sensor 400, exceptthat an upper surface of the transparent dielectric 11 is convexlycurved such that the transparent dielectric 11 acts as a microlens.

FIG. 18 is a cross-sectional view schematically illustrating an imagesensor 700 according to yet another exemplary embodiment that employsthe color filter array 10 discussed above. Referring to FIG. 18 , theimage sensor 700 may include a light sensing layer 110 having aplurality of pixels 110A, 110B, and 110C separated by a trench 111, anantireflection layer 120 disposed on the light sensing layer 110, thecolor filter array 10 having a plurality of color filters 10A, 10B, and10C and an isolation wall 13 arranged between the color filters 10A and10B and between the color filters 10B and 10C, and a plurality ofplanarization layers 121. Each of the plurality of planarization layers121 disposed between the antireflection layer 120 and each of theplurality of color filters 10A, 10B, and 10C. the image sensor 700 mayfurther include a plurality of metal grids 122. Each of the plurality ofmetal grids 122 may be disposed between two adjacent planarizationlayers 121. The isolation wall 13 may be disposed on each of the metalgrids 122.

FIG. 19 is a plan view schematically illustrating a color filter 10Aaccording to another exemplary embodiment. Referring to FIG. 19 , thecolor filter 10A may include four first Mie resonance particles 12A.Each of the first Mie resonance particles 12A may have a quartercircular shape and be disposed at a corner of the color filter 10A. Thecolor filter 10A may further include a second Mie resonance particle 12Bhaving a circular shape. The second Mie resonance particle 12B may bedisposed at center portion of the color filter 10A. The heights of thefirst and second Mie resonance particles 12A and 12B may range fromabout 200 nm to about 300 nm and diameters d of the first and second Mieresonance particles 12A and 12B may range from about 60 nm to about 180nm.

FIGS. 20A through 20E are graphs illustrating exemplary transmittancespectra for each color filter according to diameters of the first andsecond Mie resonance particles 12A and 12B. In the color filters ofFIGS. 20A through 20E, the first and second Mie resonance particles 12Aand 12B formed of polysilicon were used, and a diameter d1 of the firstMie resonance particles 12A and a diameter d2 of the second Mieresonance particle 12B were differentiated among the color filterscorresponding to FIGS. 20A through 20E, respectively. For comparison,the transmittance characteristics of related art organic color filtersare shown together by dashed line graphs.

As shown by a solid line graph in FIG. 20A, the color filter transmitsmost of the red light when d1=90 nm, d2=120 nm, p=210 nm, and h=250 nm,where p is a pitch between adjacent two color filters and h is a heightof the first and second Mie resonance particles 12A and 12B. As shown bya solid line graph in FIG. 20B, the color filter transmits most of thegreen light when d1=60 nm, d2=180 nm, p=260 nm, and h=250 nm. As shownby a solid line graph in FIG. 20C, the color filter transmits most ofthe blue light when d1=150 nm, d2=0 nm, p=270 nm, and h=200 nm. As shownby a solid line graph in FIG. 20D, the color filter transmits most ofthe magenta light when d1=110 nm, d2=60 nm, p=280 nm, and h=200 nm. Asshown by a solid line graph in FIG. 20E, the color filter transmits mostof the yellow light when d1=120 nm, d2=110 nm, p=200 nm, and h=300 nm.

FIG. 21 is a plan view schematically illustrating a color filter 10Aaccording to yet another exemplary embodiment. Referring to FIG. 21 ,the color filter 10A may include a Mie resonance particle 12 having asquare shape. The Mie resonance particle 12 may be disposed at centerportion of the color filter 10A. A width W of the Mie resonance particle12 may range from about 100 nm to about 200 nm.

FIGS. 22A through 22E are graphs illustrating exemplary transmittancespectra for each color filter according to a width of a Mie resonanceparticle 12. In the color filters of FIGS. 22A through 22E, the Mieresonance particle 12 formed of polysilicon was used, and a width w wasdifferentiated among the color filters corresponding to FIGS. 22Athrough 22E, respectively. For comparison, the transmittancecharacteristics of related art organic color filters are shown togetherby dashed line graphs.

As shown by a solid line graph in FIG. 22A, the color filter transmitsmost of the red light when w=220 nm, h=150 nm, and p=260 nm, where h isa height of the Mie resonance particle 12 and p is a pitch betweenadjacent two color filters. As shown by a solid line graph in FIG. 22B,the color filter transmits most of the green light when w=170 nm, h=200nm, and p=320 nm. As shown by a solid line graph in FIG. 22C, the colorfilter transmits most of the blue light when w=130 nm, h=200 nm, andp=260 nm. As shown by a solid line graph in FIG. 22D, the color filtertransmits most of the magenta light when w=100 nm, h=200 nm, and p=260nm. As shown by a solid line graph in FIG. 22E, the color filtertransmits most of the yellow light when w=130 nm, h=150 nm, and p=140nm.

Various exemplary embodiments of color filter arrays including aninorganic color filter, and image sensors and display devices employinga color filter array have been described above with reference to theaccompanying drawings. However, it should be understood that theexemplary embodiments described herein are to be considered in adescriptive sense only and not for purposes of limitation. Descriptionsof features or aspects within each exemplary embodiment should typicallybe considered as available for other similar features or aspects inother exemplary embodiments.

While one or more exemplary embodiments of the present disclosure havebeen described with reference to the figures, it will be understood bythose of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the present disclosure as defined by the following claims.

What is claimed is:
 1. An image sensor comprising: a light sensing layer comprising an array of a plurality of pixels arranged two-dimensionally, the plurality of pixels comprising a first pixel configured to detect light of a first wavelength range and a second pixel configured to detect light of a second wavelength range, different from the first wavelength range; and a color filter array disposed on the light sensing layer, the color filter array comprising a plurality of color filters arranged two-dimensionally, the plurality of color filters comprising a first color filter facing the first pixel and configured to transmit the light of the first wavelength range and a second color filter facing the second pixel and configured to transmit the light of the second wavelength range; wherein each of the first color filter and the second color filter comprises at least one particle configured to scatter light incident thereon and a transparent dielectric surrounding the at least one particle, wherein the color filter array comprises an isolation wall arranged between the first color filter and the second color filter and configured to prevent interactions between particles of the first color filter and particles of the second color filter.
 2. The image sensor of claim 1, wherein a refractive index of the at least one particle is greater than a refractive index of the transparent dielectric.
 3. The image sensor of claim 2, wherein the at least one particle has a refractive index greater than 3.5 with respect to visible light.
 4. The image sensor of claim 1, wherein the at least one particle is formed of at least one material selected from a group consisting of germanium (Ge), amorphous silicon (a-Si), polycrystalline silicon (p-Si), crystalline silicon (c-Si), III-V compound semiconductor, titanium dioxide (TiO2), and silicon nitride (SiNx).
 5. The image sensor of claim 1, wherein the isolation wall is formed of a first material, and the transparent dielectric is formed of a second material, different from the first material.
 6. The image sensor of claim 5, wherein the isolation wall is formed of at least one material selected from a group consisting of tungsten (W), aluminum (Al), gold (Au), silver (Ag), titanium (Ti), nickel (Ni), platinum (Pt), an alloy thereof, titanium nitride (TiN), and air.
 7. The image sensor of claim 1, wherein a thickness of each of the plurality of color filters is in a range from about 200 nm to about 300 nm.
 8. The image sensor of claim 1, wherein an aspect ratio of each of the at least one particle is in a range of about 0.5 to about
 6. 9. The image sensor of claim 1, wherein the first color filter transmits the light of the first wavelength range due to a shape, a size, and a thickness of each of the at least one particle of the first color filter and a distance between the particles of the first color filter, and wherein the second color filter transmits the light of the second wavelength range due to a shape, a size, and a thickness of each of the at least one particle of the second color filter and a distance between the particles of the second color filter.
 10. The image sensor of claim 1, wherein each of the plurality of color filters comprises a plurality of unit cells arranged periodically therein, each of the plurality of unit cells comprising a plurality of particles arranged irregularly therein.
 11. The image sensor of claim 1, wherein the isolation wall comprises a plurality of isolation members arranged along boundaries of each of the plurality of color filters, and wherein the plurality of isolation members are spaced apart from each other.
 12. The image sensor of claim 1, wherein each of the plurality of color filters comprises four first particles, each of the first particles having a quarter circular shape and being disposed at a corner of each of the plurality of color filters.
 13. The image sensor of claim 12, wherein each of the plurality of color filters further comprises a second particle, the second particle having a circular shape and being disposed at center portion of each of the plurality of color filters.
 14. The image sensor of claim 1, wherein each of the plurality of color filters comprises a square shaped particle, the square shaped particle being disposed at center portion of each of the plurality of color filters.
 15. The image sensor of claim 1, further comprising: a transparent spacer layer disposed on the color filter array; and a plurality of color separation elements disposed in the transparent spacer layer, the plurality of color separation elements configured to direct the light of the first wavelength range toward the first pixel and to direct the light of the second wavelength range toward the second pixel, wherein the color separation element is formed of a material having a refractive index greater than that of the transparent spacer layer.
 16. The image sensor of claim 15, further comprising: an additional light sensing layer disposed on the transparent spacer layer, the additional light sensing layer comprising a third pixel configured to absorb and detect light of a third wavelength range, different from the first wavelength range and the second wavelength range, and to transmit the light of the first wavelength range and the light of the second wavelength range.
 17. The image sensor of claim 16, further comprising: a plurality of driving signal lines extending from the light sensing layer to the additional light sensing layer, the plurality of driving signal lines configured to transmit driving signals to the additional light sensing layer or to receive data signals from the additional light sensing layer.
 18. The image sensor of claim 17, wherein the isolation wall comprises a conductive metallic material and the plurality of driving signal lines extend to the additional light sensing layer through the isolation wall.
 19. The image sensor of claim 16, further comprising: a first transparent electrode disposed on a lower surface of the additional light sensing layer; and a second transparent electrode disposed on an upper surface of the additional light sensing layer. 